1/* crc32.c
2   Copyright (C) 2009 Free Software Foundation, Inc.
3
4   This file is part of the libiberty library.
5
6   This file is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2 of the License, or
9   (at your option) any later version.
10
11   In addition to the permissions in the GNU General Public License, the
12   Free Software Foundation gives you unlimited permission to link the
13   compiled version of this file into combinations with other programs,
14   and to distribute those combinations without any restriction coming
15   from the use of this file.  (The General Public License restrictions
16   do apply in other respects; for example, they cover modification of
17   the file, and distribution when not linked into a combined
18   executable.)
19
20   This program is distributed in the hope that it will be useful,
21   but WITHOUT ANY WARRANTY; without even the implied warranty of
22   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
23   GNU General Public License for more details.
24
25   You should have received a copy of the GNU General Public License
26   along with this program; if not, write to the Free Software
27   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
28*/
29
30#ifdef HAVE_CONFIG_H
31#include "config.h"
32#endif
33
34#include "libiberty.h"
35
36/* This table was generated by the following program.  This matches
37   what gdb does.
38
39   #include <stdio.h>
40
41   int
42   main ()
43   {
44     int i, j;
45     unsigned int c;
46     int table[256];
47
48     for (i = 0; i < 256; i++)
49       {
50	 for (c = i << 24, j = 8; j > 0; --j)
51	   c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);
52	 table[i] = c;
53       }
54
55     printf ("static const unsigned int crc32_table[] =\n{\n");
56     for (i = 0; i < 256; i += 4)
57       {
58	 printf ("  0x%08x, 0x%08x, 0x%08x, 0x%08x",
59		 table[i + 0], table[i + 1], table[i + 2], table[i + 3]);
60	 if (i + 4 < 256)
61	   putchar (',');
62	 putchar ('\n');
63       }
64     printf ("};\n");
65     return 0;
66   }
67
68   For more information on CRC, see, e.g.,
69   http://www.ross.net/crc/download/crc_v3.txt.  */
70
71static const unsigned int crc32_table[] =
72{
73  0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
74  0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
75  0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
76  0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
77  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
78  0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
79  0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
80  0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
81  0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
82  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
83  0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
84  0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
85  0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
86  0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
87  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
88  0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
89  0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
90  0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
91  0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
92  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
93  0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
94  0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
95  0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
96  0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
97  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
98  0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
99  0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
100  0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
101  0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
102  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
103  0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
104  0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
105  0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
106  0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
107  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
108  0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
109  0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
110  0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
111  0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
112  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
113  0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
114  0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
115  0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
116  0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
117  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
118  0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
119  0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
120  0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
121  0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
122  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
123  0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
124  0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
125  0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
126  0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
127  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
128  0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
129  0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
130  0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
131  0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
132  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
133  0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
134  0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
135  0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
136  0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
137};
138
139/*
140
141@deftypefn Extension unsigned int crc32 (const unsigned char *@var{buf}, int @var{len}, unsigned int @var{init})
142
143Compute the 32-bit CRC of @var{buf} which has length @var{len}.  The
144starting value is @var{init}; this may be used to compute the CRC of
145data split across multiple buffers by passing the return value of each
146call as the @var{init} parameter of the next.
147
148This is intended to match the CRC used by the @command{gdb} remote
149protocol for the @samp{qCRC} command.  In order to get the same
150results as gdb for a block of data, you must pass the first CRC
151parameter as @code{0xffffffff}.
152
153This CRC can be specified as:
154
155  Width  : 32
156  Poly   : 0x04c11db7
157  Init   : parameter, typically 0xffffffff
158  RefIn  : false
159  RefOut : false
160  XorOut : 0
161
162This differs from the "standard" CRC-32 algorithm in that the values
163are not reflected, and there is no final XOR value.  These differences
164make it easy to compose the values of multiple blocks.
165
166@end deftypefn
167
168*/
169
170unsigned int
171xcrc32 (const unsigned char *buf, int len, unsigned int init)
172{
173  unsigned int crc = init;
174  while (len--)
175    {
176      crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ *buf) & 255];
177      buf++;
178    }
179  return crc;
180}
181